Rotary electric machine comprises a stator and a rotor mounted on a shaft. The electric machine comprises a casing carrying the stator. The shaft of the rotor is linked in rotation to the casing for example by means of ball bearings.
The rotor comprises a core formed by a stack of flat metal plates. The rotor comprises poles formed for example by permanent magnets positioned within cavities realized in the magnetic mass of the rotor, as it is described in document EP0803962. Alternatively, in a so-called salient poles architecture, the poles are formed by coils wound around arms of the rotor.
Furthermore, the stator comprises a core constituted by a stack of flat metal plates and a stator winding. The stator winding comprises a plurality of phase coils of the type in which each phase coil consists of conductors which are arranged in slots of the core associated with the phase, forming overall a spiral coaxial to an axis of the core. The winding therefore consists of a set of turns of the phase coils radially superimposed. Each phase coil comprises end-loop portions positioned alternatively on each side of the stator. Those end-loop portions establish a link between straight portions positioned inside the slots of the stator.
To improve the performance of the electric machine, it is preferable to fill the slots of the core to the maximum, while optimizing the flow sections of the magnetic flux. To this end, document U.S. Pat. No. 6,459,187 teaches the realization of a same layer of conductors. However, because of the high number of wires (at least two wires per phase, i.e 12 wires in total for a six phases winding), the coupling of the different phase coils between them is difficult to perform.